Referring to FIG. 1, a traditional disk drive 20 has a bottom part and a top cover 29 which are combined with each other. The bottom part comprises a head stack assembly (HSA) 17 with a slider (not shown), a disk 11, and a ramp 15 mounted on a bottom cover 19. The disk 11 is mounted on a spindle motor 31 which causes the disk 11 to spin, and a voice-coil motor 13 is provided for controlling the motion of the HSA 17 and thus controlling the slider thereon to move from track to track across the surface of the disk 11 to read data from or write data to the disk 11. The ramp 15 transitions the slider off-of and back-onto a flying area above the surface of the rotating disk 11, which typically interacts with a lift tab at an end of the HSA 17.
However, the rework of the HSA 17 of the traditional disk drive 20, especially the slider, is not convenient because it must remove the HSA 17 from the bottom cover 19 before rework. In order to simplify the rework of the HSA 17, it attempts to mount the HSA 17 on the top cover 29. In this way, it is not required to remove the HSA 17 from the top cover 29 when reworking the HSA 17, especially the slider, but only need to separate the top cover 29 with the bottom part. But if the HSA 17 is mounted on the top cover 29, it is difficult to load the lift tab of the HSA 17 on the ramp 15 to get an initial status when assembling the top cover 29 with the bottom part because there exists a free angle between the suspension at a free status and a loading status, which results in a difference therebetween at a horizontal direction.
It is therefore desirable to provide a disk drive unit with its disk and HSA assembled in two different halves, a ramp tool for assembling such disk drive units and an assembly method of disk drive unit using the ramp tool to solve the above-mentioned problems.